Amp only turns on in cd mode

hello i was just wondering if u can help me out i just installed an aftermarket head unit into a 1993 Olds cutlass superme and it seems that it only the amp wants to turn on when cd is on but cd only reads error so i am not sure if the head unit it is done or maybe a wire is maybe messed but i hope u can let me know cause the radio stations suck here lol but anyways good luck and thanks for ur time